Abstract
OBJECTIVES: Leukocyte NADPH oxidase, which is active in neutrophils, is a membrane-bound enzyme that catalyzes the reduction of oxygen to O2(-) by using NADPH as an electron donor. Previously, we reported that casein kinase 2 (CK2), a ubiquitous and highly conserved Ser/Thr kinase, is responsible for p47(phox) phosphorylation and that phosphorylation of p47(phox) by CK2 regulates the deactivation of NADPH oxidase. METHODS: Here, we report that the residue Cys(196) of p47(phox) is a target of S-nitrosylation by S-nitrosothiol and peroxynitrite and that this modification enhanced phosphorylation of p47(phox) by CK2. RESULTS: S-Nitrosylated p47(phox) enhanced CK2 b subunit binding, presumably due to alterations in protein conformation. DISCUSSION: Taken together, we propose that S-nitrosylation of p47(phox) regulates the deactivation of NADPH oxidase via enhancement of p47(phox) phosphorylation by CK2.